The PID may have some type of visual blinking for an alarm, but it it common to use something like this to get audio and a more striking visual. http://www.auberins.com/index.php?ma...roducts_id=215
Yes, you can stop the alarm on the PID. However, it is common to use some type of switch to shut the audible alarm off while hitting the multiple buttons on the PID to stop the alarm. Kal has a on/off rotary switch. BadNews has a momentary switch that he has to hold while he resets the PID, which has the advantage that you cannot "forget" that you silenced the alarm. I have considered a normally closed, illuminated pushbutton that would only be illuminated when the alarm has been disabled, as a visual clue that it has been disabled.